Flow divider



Jan. 14, 1969 R, R. DAvlDsON 3,421,532

FLOW DIVIDER Filed oet. 14, 1964 sheet of 2 L, rea

Faffpavl'ds'an Y Jan 14, 1969` R. R. DAVIDSON 3,421,532

FLow DIVIDER l Filed oct. 14, 1964 sheet 2 'of 2 47 f5 20 155 z5 50 /5 ,f2

United States Patent O 3,421,532 FLOW DIVIDER Robert R. Davidson, Auburn, Ind., assignor to Borg Warner Corporation, Chicago, Ill., a corporation of Illinois Filed Oct. 14, 1964, Ser. No. 403,865 U-S. Cl. 137-101 Int. Cl. G0511 11/103; F17d 3/00; F01b 25/02 6 Claims ABSTRACT F THE DISCLOSURE This invention relates to a multiple stage fiow divider mechanism and, more particularly, to a multiple stage ow divider mechanism having associated therewith a primary and a secondary circuit.

Briefly described, a piston and a cylinder, together with a plurality of ports and a plurality of orifices associated therewith provide a means to divide the flow of uid from a source of fluid under pressure such as, for example, the output flow from a pump. The flow divider mechanism includes a primary circuit which is a priority ow circuit and a secondary circuit which is an excess flow circuit.

During the first stage of operation, the primary circuit has priority over the secondary circuit and thus, as the flow of fluid to the divider mechanism increases up to the capacity of the primary circuit, all of the uid passes through the primary circuit. As the ow increases above the capacity of the primary circuit and up to the capacity necessary to switch the divider mechanism into the second stage of operation, all of the additional fluid passes through the secondary circuit. During the second stage of operation, the primary circuit remains effective to function as a priority circuit and the secondary circuit continues to act as an excess flow circuit.

An important feature of the flow divider mechanism is that during operation of the flow divider mechanism, the primary and secondary circuits function independently of each other. During both stages of the operation of the flow divider mechanism, either one or both of the circuits can be subjected to back pressure without adversely affecting the performance of the other circuit.

Other, and more particular, objects and advantages of this invention will be apparent from the following description, taken in connection with the annexed drawings, in which:

FIGURE l is a cross-sectional view of the ow divider mechanism illustrating the relative position of the piston in the housing under one set of fiow conditions;

FIGURE 2 is a cross-sectional view of the fiow divider mechanism illustrating the relative position of the piston in the housing under another set of flow conditions;

FIGURE 3 is a cross-sectional view of the flow divider mechanism illustrating the relative position of the piston in the housing under another set of ow conditions;

FIGURE 4 is a cross-sectional view of the flow divider mechanism illustrating the relative position of the piston in the housing under another set of flow conditions;

FIGURE 5 is a cross-sectional view of the ow divider mechanism illustrating the relative position of the piston in the housing under another set of ow conditions; and

FIGURE 6 is a cross-sectional View of the fiow divider ice ymechanism illustrating the relative position of the piston in the housing under still another set of flow conditions.

Referring to the drawing and, more particularly, FIG- URE l, a fluid passage 10 is formed within a body 12. A housing 14 having spaced apart lands 16a, 16b and 16e is positioned within the body 12. Seal means 18a and 18b extend in lands 16a and 16b respectively to provide a fluid-tight fit between the lands 16a and 16b and the ibody 12 to provide an annular secondary circuit chamber 20 between the housing 14 and the body 12. A secondary circuit passageway 22 provides a means to remove fluid from the annular chamber 20. A primary circuit passage 24 is in fluid communication with the annular primary circuit chamber 26 4which is formed between the housing 14 and the body 12 between lands 16b and 16C. A piston 28 is slidably positioned within bore 30. A resilient mernber 32 is positioned, for example, between the body 12 and the piston 28 to bias the piston 28 to the left with respect to the housing 14 as viewed in FIGURE l.

The piston 28 includes an end 34 having a rst orifice 36 formed therein. The piston includes an inner wall 38 having a second orifice 40 formed therein. The end portion 34 and inner wall 38 together with the wall of the piston 28 form a first chamber 42 in one end of the piston 28. A plurality of secondary piston ports 44 provide cornrnunication between chamber 42 and bore 30 of the housing 14.

The portion of the piston to the right of the inner wall 38, together with the bore 30 of the housing member 1-4, forms a second chamber 46. A first series of ports 48 provides communication between the second chamber 46 and the bore 30 of the housing 14. A second series of ports 50 axially spaced from the first series of ports provides communication between the second chamber and the bore 30 of the housing 14. The housing 14 includes ports 52 which provide communication lbegtween bore 30 and the annular chamber 20. A housing 14 also includes ports 54a and 54h which provide communication between bore 30 and annular chamber 26.

In operation, the resilient 'member 32 provides an initial bias to position the piston 28 adjacent the left end of the bore 30 which is formed in the housing 14. The operation of the flow divider mechanism will be explained in stepped lncrements of flow conditions.

Step 1 of Stage 1 This flow condition is from initial flow rate to a flow rate equal to the capacity of the primary circuit under Stage l operation. As an initial fluid flow rate is established in the passage 10, the fluid flows through the orifice 36 located in the end portion 34 of the piston 28. This initial quantity of uid passes from chamber 42 through orifice 40 into the second chamber 46 out port 50 in piston 28, through port 54a in housing 14 into annular chamber 26 and thence into the primary circuit passage 24. Under this set of flow rate conditions, the ports 44 in piston 28 are not aligned with ports 52 in housing I4 and thus all of the fluid passes from passage 10 into the primary circuit.

Step 2 of Stage 1 This flow condition is from a rate above the capacity of the primary circuit to a rate equal to the rate which initiates Stage 2 operation. This step further includes a condition wherein the hack pressure, or operating pressure, in the secondary circuit is maintained at a value in excess of the pressure of the fluid in the primary circuit.

As the fiuid rate is increased to a value in excess of the capacity of the primary circuit, the fluid owing through orifice 40 creates a pressure differential thereacross. This differential is of a suicient magnitude to overcome the resiliency of spring 32. This, in turn, causes the piston 28 to shift to the right with respect to the housing 14.

3 Under this set of flow conditions (see FIGURE 1), the ports 50 in piston 28 are aligned with ports 54a in housing 14 and the ports 44 in piston 28 are aligned with ports 52 in the housing 14. Thus, a portion of the fluid passes from chamber 46 through ports 50, ports 54a into charnber 26, and thence into the primary circuit passage 24 and the remaining portion passes from chamber 42 through ports 44, ports 52 into chamber 20, and thence into the secondary circuit passage 22. The fiuid fiowing through orifice 36, under these conditions, does not create a pressure differential of sufficient magnitude to infiuence the position of the piston 28. The controlling orifice under this set of iiow conditions is orifice 40. Metering of fiuid to the primary circuit is achieved, in part, by the relative positions of the ports 50 in the piston 28 and the ports 54a in the housing 14. These ports establish and maintain a substantially constant pressure drop there- `across and thus maintain a substantially constant quantity of flow to the primary circuit. All flow in excess of the ow to the primary circuit is diverted to the secondary circuit.

Step 3 of Stage 1 The flow rate for this step is within the same limits as Step 2 of Stage 1; however, the back pressure, or operating pressure, in the primary circuit is at a value in excess of the operating pressure in the secondary circuit (see FIGURE 2).

Under this set of conditions, the orifice 40 and the pressure differential associated therewith is effective to shift the piston 28 against the action of the resilient member 32, to the right with respect to housing 14. Metering of the fluid to the primary circuit is accomplished, in part, by the relative positions of the ports 44 and 52 which establish a substantially constant pressure drop thereacross. This pressure drop results in a substantially constant quantity of fiuid being diverted to the primary circuit with the exces fluid being directed to the secondary circuit.

Transition from Stage 1 t0 Stage 2 As the flow rate exceeds the upper limit of Stage 1, mentioned hereinabove, the orifice 36 becomes the controlling orifice. The pressure differential created across orifice 36 tends to shift the piston 28 with respect to the housing 14 to a new control position as illustrated in FIGURES 3 Aand 4. As the piston 28 tends to complete its movement with respect to the housing 14 into the second stage control position (FIGURE 4), the ports 44 become aligned with the intermediate chamber 47 which chamber 47 is in communication with ports 48, This flow path, i.e., from chamber 42 through ports 44, into chamber 47, and thence to chamber 46 by way of ports 48 functions as a -bypass which is in parallel wtih orifice 40. The effect of the aforementioned bypass is to increase the capacity of the primary circuit.

Step I of Stage 2 The flow rate condition for this step is above the maximum Stage 1 rate with the back pressure, or operating pressure, in the secondary circuit maintained at a pressure above the operating pressure of the primary circuit (FIGURE 5). Under this set of conditions, the fiuid fiowing through the orifice 40 and the bypass means (ports 44, chamber 47 and ports 48) is effective to shift the piston 28 lagainst the action of the resilient member 32 to the right with respect to the housing 14 as illustrated in FIGURE 5. Metering of the iiuid to the primary circuit is accomplished, in part, by the relative position of ports 50 and 54!) which function to establish a substantially constant pressure drop thereacross. This results in a substantially constant quantity of uid being diverted to the primary circuit with the excess fluid being directed to the secondary circuit.

4 Step 2 of Stage 2 The fiow rate for this step is within the same limits as Step l of Stage 2 hereinabove set forth; however, the back pressure or operating pressure in the primary circuit is maintained above the operating pressure of the Secondary circuit. Under this set of conditions, the fluid flowing through the orifice 40 and the bypass means is effective to shift the piston 28 :against the action of the resilient member 32 to the right with respect to the housing 14 (FIGURE 6). Metering of the fluid to the primary circuit is accomplished, in part, by the relative position of the end of the piston 28 with respect to the passage 51 in the housing 14 (see FIGURE 6). Thus, a substantially constant quantity of fiuid is directed to the primary circuit with the remaining quantity being -diverted to the secondlary circuit.

The foregoing description of a preferred embodiment of the invention has been shown and described for the purpose of illustrating the principles of the invention and is subject to change without departure from the spirit and the intent of the invention. The invention is to be limited only by the scope of the following claims.

What is claimed is:

1. A flow divider mechanism comprising a housing having a bore therein, an inlet passage in communication with said bore, housing primary port means in said housing, housing secondary port means in said housing, a piston having a first chamber and having a second chamber, said piston being slidably positioned within said bore, a first orifice providing com-munication between said bore :and said first chamber, a second orifice providing communication between said first chamber and said second chamber, piston primary port means in said second chamber operatively associated with said housing primary port means, piston secondary port means in said first chamber operatively associated with said housing secondary port means, bypass flow means responsive to the position of the piston with respect to said housing to allow passage of tiuid between said first chamber and said second chamber, and means to bias said piston With respect to said housing.

2. A flow divider mechanism comprising a housing having a bore therein, an inlet passage in communication with said bore, housing primary port means in said housing, housing secondary port means in said housing, a piston having a first chamber and having a second chamber, said piston being slidably positioned within said bore, a first orifice providing communication between said bore and said first chamber, a second orifice providing corn- Imunication between said first chamber and said second chamber, piston primary port means in said second chamber operatively associated with said housing primary port means, piston secondary port means in said first chamber operatively associated with said housing secondary port means, flow sensitive bypass flow means effective in response to the position of said piston with respect to said housing to permit fluid to flow from said first chamber to said second chamber, and means to bias said piston with respect to said housing.

3. A ow divider mechanism comprising a housing having a bore therein, a piston slidably positioned within the bore, said housing including an inlet passage, a primary circuit passage and a secondary circuit passage, a fiow path between said inlet passage and said primary and secondary circuit passages including primary circuit ports, and secondary circuit ports, defined by said piston and said housing in combination, a pair of spaced apart oriiice means in said piston arranged with the first of said orifice means disposed intermediate said inlet passage and said secondary circuit ports and the second of said orifice means disposed'intermediate said first orifice means and said primary circuit ports, said housing and said piston in combination further defining by-pass fiow means disposed intermediate said primary circuit ports and said secondary circuit ports sensitive to flow into said inlet passage to by-pass said second of said orifice means in response to a predetermined flow and means to provide an initial bias to shift said piston in a first direction with respect to said housing.

4. A flow divider mechanism comprising a housing having a bore therein, a piston reciprocally positioned within said bore, said housing including an inlet passage, a primary circuit passage, and a secondary circuit passage, a flow path between said inlet passage and said primary and secondary circuit passages including primary circuit ports, and secondary circuit ports, formed by said housing and piston in combination, said piston including a first chamber and a second chamber, and a first orifice and a second orifice, said first chamber being in communication with said second chamber through said second orifice, and in communication with said primary circuit passage through said primary circuit ports, said second chamber being in communication with said inlet passage through said first orifice and communicating with said secondary circuit passage through said secondary circuit ports, said housing and said piston in combination further dening by-pass fiow means disposed intermediate said primary circuit ports and said secondary circuit ports sensitive to ow into said inlet passage to by-pass said second of said orifices in response to a predetermined flow and resilient means to bias said piston with respect to said housing.

5. A ow divider mechanism comprising a housing having a bore therein, a piston reciprocally positioned in said bore, said housing including an inlet passage, a primary circuit passage, a secondary circuit passage, a ow path between said inlet passage and said primary and secondary circuit passages including first ports in said housing communicating with said primary circuit passage and second ports in said housing communicating with said secondary circuit passage, a first orifice in said piston intermediate said inlet passage and said secondary circuit passage, a second orifice in said piston intermediate said first orifice and said primary circuit passage, first ports in said piston adapted to communicate with said first ports of said housing and second ports in said piston adapted to communicate with said second ports of said housing, and by-pass flow means responsive to the position of said piston with respect to said housing to allow fiow of fluid from said inlet passage to said secondary circuit passage, said piston being shiftable with respect to said housing in a first stage of operation to align said ports in said piston and said ports in said housing to establish a first predetermined ow into said primary circuit passage, with the excess above said first predetermined flow fiowing to said secondary circuit passage through said second ports and further being shiftable in a second stage of operation to align said ports in said piston and said ports in said housing to establish a second predetermined flow into said primary circuit passage with the excess above said predetermined ow flowing into said secondary circuit passage, resilient means to bias said piston with respect to said housing.

6. A fiow divider mechanism comprising a housing having a bore therein, a piston reciprocally positioned in said bore, said housing including an inlet passage, a primary circuit passage, a secondary circuit passage, a flow path between said inlet passage and said primary and secondary circuit passages including, first ports in said housing communicating with said primary circuit passage, and second ports in said housing communicating with said secondary circuit passage, a first chamber, a second chamber, a first orifice, a second orifice, each formed in said piston, first ports in said piston adapted to communicate with said first ports of said housing and second ports in said piston adapted to communicate with said second ports of said housing, said first chamber being in communication with said second chamber through said second orifice and communicating with said primary circuit passage through said first ports, said second chamber being in communication with said inlet passage through said first orifice and communicating with said secondary circuit passage through said second ports, and by-pass ow means responsive t0 the position of said piston with respect to said housing including means to allow flow of fiuid to by-pass said second orifice and further means to allow flow of fiuid from said inlet passage to said secondary circuit passage in response t0 predetermined fiow, said piston being shiftable with respect to said housing in a first stage of operation to align said first ports in said piston with said first ports of said housing to establish a first predetermined fiow into said primary circuit passage and to align said second ports of said piston with said second ports of said housing to allow excess flow above said first predetermined flow to fiow to said secondary circuit passage and further being shiftable in a second stage of operation to align said first ports of said piston with said first ports in said housing to establish a second predetermined flow to said primary circuit passage and to align said second ports of said piston with said second ports of said housing to allow excess iow above said second predetermined fiow to fiow to said secondary circuit passage, resilient means to bias said piston with respect to said housing.

References Cited UNITED STATES PATENTS 3,142,962 8/1964 Lohbauer 60-525 XR WILLIAM F. ODEA, Primary Examiner.

D. J'. ZOBKIW, Assistant Examiner. 

